Periodic Reporting for period 1 - WINTERC-3D (Thermochemical imaging of the Earth’s mantle: Global inversion of seismic waveforms, satellite gravity data and surface elevation)
Reporting period: 2015-03-01 to 2017-02-28
The use of a new type of measurement (GOCE satellite gradiometric data, initially intended to study the ocean circulation) to image the solid Earth is of great interest to the Earth Science community at present. The impact of WINTERC-3D in this sense is twofold: i) a new integrative approach to exploit these data and is provided to the scientific community; and ii) Space agencies and technology companies get feedback about on-board equipment specifications and general planning for future missions. As a future reference Earth model, WINTERC-3D will contribute to European excellence and competitiveness by providing thorough basis for global and regional studies ranging from the origin and evolution of the Earth to mantle convection, dynamics of plate tectonics, and to ore and diamond resource assessment and prospecting.
A unique aspect of this proposal is the significant enhancement of the use of a new class of satellite observation data. Showing the ability of these remote sensing data to illuminate the solid Earth (with society-relevant implications for basic dynamic processes responsible for global seismicity, volcanism, and for natural resource assessment) has important outreach potential for a broad audience (“How deep inside the Earth can we see from a satellite?”). The communication and public engagement strategy of WINTERC-3D are designed so as to appropriately deliver this potential to society in the form of outreach activities.
A parallelized integrated geophysical-petrologocal software to invert seismic waveform data (WINTERC) has been developed and tested with synthetic data sets. WINTERC runs a forward solver where all relevant rock physical properties modelled are computed within a thermodynamically self consistently framework allowing for a direct parameterization of the thermochemical conditions within the Earth. The 3D waveform data have been transformed into phase velocity dispersion curves for both Rayleigh and Love surface-waves that can be modelled in 1D beneath each particular geographical location.
WINTERC inverts the dispersion curves along with surface topography and heat flow using a non-linear gradient search algorithm. The parameter space comprises crustal structure, mantle structure and seismic radial anisotropy. To handle the very complex parameter space a further inversion for the dumping parameters themselves is carried out in the regularization.
A global gravity solver built on spherical harmonic formalism (GGSH) has been developed to compute synthetic gravity observables based on any given 3D distribution with the Earth. The next step consists on inverting satellite and terrestrial gravity data for the composition of the upper mantle assuming (or strongly dumping towards) the temperature distribution constrained by the seismic, elevation and heat flow data. The resulting 3D temperature and compositional model will be tested against appropriate 3D forward solvers to enforce internal consistency of all constraining data sets and its uncertainty will be assessed through selective Monte Carlo analysis and projection subspaces grids.
WINTERC-3D has represented an excellent platform to enhance the scientific career of J. Fullea in terms of leadership, networking and management skills. Based on the positive outcome of WINTERC-3D, J. Fullea has secured funding to support a research team of four postdoctoral scholars in DIAS working on complementary strands of integrated geophysical-petrological modelling of the Irish on- and off-shore crustal and mantle structure and evolution.
Furthermore, the outcomes of WINTERC-3D attracted the interest of other research groups in Europe, and as a result the research team of WINTERC-3D joined, as co-PI’s, an European Space Agency international project aimed at exploiting gravity and magnetic satellite data to explore the global structure and evolution of the Earth (“3D Earth, a dynamic, living planet”, https://www.3dearth.uni-kiel.de/en).